Physiological assessment of baseline HRV
Data were acquired using two different kinds of devices: BiopacMP150/160 (Biopac Systems Inc., California, USA), and Polar (Polar V800 H7 & H10, Kempele, Finland), at a sampling frequency of 1000 Hz for all devices. The electrocardiogram (ECG) electrode placements were corresponding to each device’s instruction manual. There were two different baseline conditions in the samples of this study: 1) Rest, sitting upright in a chair with palm up and eyes open naturally (72.3 % of the total sample); 2) Vanilla, also sitting upright in a chair and reading magazines (27.6 % of the total sample). Data collection was performed in a controlled environment. All data included baseline measurement for 5 or 10 minutes to calculate resting-state HRV. For the data which lasted 5 minutes, we calculated the mean values of the time intervals between R peaks over the 5 minutes. For the data which lasted 10 minutes, we used the last 5 minutes of cardio data because the last 5 minutes of heart rate were more stable and had fewer artifacts than those of the first 5 minutes.